1. Field of the Invention
The present invention relates to a photoelectric conversion device and to an electronic device including the photoelectric conversion device. The present invention particularly relates to a photoelectric conversion device which can correct a signal output from the photoelectric conversion device in accordance with external environment and output the corrected signal, and to an electronic device including the photoelectric conversion device.
2. Description of the Related Art
A number of photoelectric conversion devices for detecting light are known; for example, a visible light sensor is commercially practical. A photoelectric conversion device is commonly used for devices which need illuminance adjustment, on/off control, or the like depending on the human living environment.
Some display devices detect its ambient brightness and adjust the display luminance. This is because the visibility can be improved and unnecessary electric power of the display device can be reduced by a photoelectric conversion device which detects ambient illuminance to obtain appropriate display luminance. For example, a mobile phone and a computer having a display portion are given as a display device which includes a photoelectric conversion device for adjusting luminance.
A photoelectric conversion device uses a photoelectric conversion element such as a photodiode for a light sensing portion and detects illuminance based on the amount of current (output current) which flows through the photoelectric conversion element. The photoelectric conversion device commonly includes a correcting circuit for correcting output current, dark current, etc. In Patent Document 1, a structure is described which is designed to detect an output current flowing from a photodiode and which employs a means for limiting a current which flows to the photodiode when a current which flows through the photodiode is greater than a predetermined value.